This invention has to do with bubble tonometers, and more particularly it is concerned with bubble tonometers having multiple independent flow paths which are maintained within a common environmentally controlled locus whereby sets of differing or identical blood samples may be simultaneously prepared under indentical though dynamic conditions.
Bubble tonometers have long been known; classically the bubble tonometer was designed as a closed system to prepared blood samples of different gas contents for the determination of oxygen disassociation curves. Bubble tonometers are simple devices which required no outside mechanism to agitate the blood and rapid equilibration is achieved. The history of bubble tonometers and a different type of bubble tonometer is discussed in an article entitled "Determination of the Blood/Gas Factor of the Oxygen Electrode Using a New Tonometer" by A. P. Adams and J. O. Morgan-Hughes published at Vol. 39, pp. 107-113 (1967) in the British Journal of Anaesthesia. Modern requirements for bubble tonometers are primarly fo maintaining blood/gas quality control. Thus in 1977 the Food and Drug Administration published a draft standard for blood/gas analysis establishing blood tonometery as a recommended procedure for blood/gas quality control. It was further recommended that such quality control should be maintained with three levels of tonometered blood at least once a week or every time an operating change is made, e.g. in membranes, electrodes, gas system shut-down and start-up. Daily performance is preferred. Use of the same gases to equilibrate the buffer is likewise recommended.
In general there is need to inexpensively and accurately produce blood and buffer controls at any desired oxygen level, either the low end, useful, for example, in connection with neonatal intensive care, or at the high end for supporting open heart surgery, or when conducting shunt studies.
It is highly undesirable to have simultaneous control of the various samples and buffer being prepared and it is to this need that the present invention is particularly directed.